Developing agent and developing device using the same

Abstract

A developing agent comprising toner particles and carrier particles, the toner particles including less than 21% of particles having a roundness of less than 0.93, and containing a binder resin, a coloring agent, and an charge controlling agent free from heavy metals.

We claim: 
     
       1. A developing agent comprising toner particles and carrier particles, said toner particles being obtained by pulverizing a kneaded mass of a toner material, including less than 21% of particles having a roundness of less than 0.93, and containing a binder resin, a coloring agent, and a charge controlling agent free from heavy metals, wherein the product between the toner particle diameter (μm) and the carrier particle diameter (μm) falls within a range defined in the following formula:   252≦A·B≦522        where A is a 50% average diameter of the toner particles, and B is a 50% average diameter of the carrier particles, and   said toner particles have a 50% average particle diameter of 7.0 to 9.0 μm, and said carrier particles have a 50% average particle diameter of 35 to 90 μm.   
     
     
       2. The developing agent according to claim 1, wherein said charge controlling agent is free from chromium. 
     
     
       3. A developing agent comprising toner particles and carrier particles, said toner particles being obtained by pulverizing a kneaded mass of a toner material, including less than 21% of particles having a roundness of less than 0.93, and containing a binder resin, a coloring agent, and a charge controlling agent consisting of a complex compound having one of iron and zinc as a central metal, wherein the product between the toner particle diameter (μm) and the carrier particle diameter (μm) falls within a range defined in the following formula:   252≦A·B≦522        where A is a 50% average diameter of the toner particles, and B is a 50% average diameter of the carrier particles, and   said toner particles have a 50% average particle diameter of 7.0 to 9.0 μm, and said carrier particles have a 50% average particle diameter of 35 to 90 μm.   
     
     
       4. The developing agent according to claim 1, wherein said charge controlling agent comprises an organic-based material as a main component. 
     
     
       5. The developing agent according to claim 1, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C1) given below: ##STR10## 
     
     
       6. The developing agent according to claim 1, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C2) given below: where X denotes ##STR11## (a substituent such as an alkyl group may be substituted), ##STR12## (Z is a hydrogen atom, a halogen atom or a nitro group), ##STR13## (R is a hydrogen atom, C 1-5  alkyl or alkenyl; ##STR14## A.sup.⊕ represent H.sup.⊕, Na.sup.⊕, NH 4 .sup.⊕ or an aliphatic ammonium. 
     
     
       7. The developing agent according to claim 1, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C3) given below: ##STR15## 
     
     
       8. The developing agent according to claim 1, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C4) given below: 
     
     
       9. The developing agent according to claim 1, wherein said roundness of the toner particle is defined by formula (M1) given below:   X/Y                                                        (M1)     where:    X is the circumferential length of a circle having an area equal to that of the projected image of the particle; and   Y is the actually measured circumferential length of the projected image of the particle.   
     
     
       10. The developing agent according to claim 1, wherein said charge controlling agent the product between the toner particle diameter (μm) and the carrier particle diameter (μm) falls within a range defined in formula below:   300≦A·B≦500      where A is a 50% average diameter of the toner particles, and B is a 50% average diameter of the carrier particles.   
     
     
       11. A developing device comprising developing means arranged to face an image carrier, supporting a developing agent and supplying the supported developing agent onto said image carrier so as to perform development, said developing agent comprising toner particles and carrier particles, said toner particles including at most 21% of particles having a roundness of 0.93 or less, and containing a binder resin, a coloring agent, and an charge controlling agent free from heavy metals. 
     
     
       12. The developing device according to claim 11, wherein said charge controlling agent is free from chromium. 
     
     
       13. The developing device according to claim 11, wherein said charge controlling agent consists of a complex compound having one of iron and zinc as a central metal. 
     
     
       14. The developing device according to claim 11, wherein said charge controlling agent comprises an organic-based material as a main component. 
     
     
       15. The developing device according to claim 11, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C1) given below: ##STR16## 
     
     
       16. The developing device according to claim 11, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C2) given below: where X denotes ##STR17## (a substituent such as an alkyl group may be substituted), ##STR18## (Z is a hydrogen atom, a halogen atom or a nitro group), ##STR19## (R is a hydrogen atom, C 1-5  alkyl or alkenyl; ##STR20## and A.sup.⊕ represent H.sup.⊕, Na.sup.⊕, NH 4 .sup.⊕ or an aliphatic ammonium. 
     
     
       17. The developing device according to claim 11, wherein said charge controlling agent, which is free from a heavy metal, includes a compound represented by structural formula (C3) given below: ##STR21## 
     
     
       18. The developing device according to claim 11, wherein said charge controlling agent, which does not contain a heavy metal, includes a compound represented by structural formula (C4) given below: 
     
     
       19. The developing device according to claim 11, wherein said roundness of the toner particle is defined by formula (M1) given below:   X/Y                                                        (M1)     where    X is the circumferential length of a circle having an area equal to that of the projected image of the particle; and   Y is the actually measured circumferential length of the projected image of the particle.   
     
     
       20. The developing device according to claim 11, wherein said charge controlling agent the product between the toner particle diameter (μm) and the carrier particle diameter (μm) falls within a range defined in formula below:   300≦A·B ≦500      where A is a 50% average diameter of the toner particles, and B is a 50% average diameter of the carrier particles.   
     
     
       21. The developing device according to claim 11, wherein said charge controlling agent the product between the toner particle diameter (μm) and the carrier particle diameter (μm) falls within a range defined in formula below:   252≦A·B≦522      where A is a 50% average diameter of the toner particles, and B is a 50% average diameter of the carrier particles.   
     
     
       22. The developing device according to claim 20, wherein a 50% average diameter of the toner particles falls within a range of between 7.0 and 9.0 μm, and a 50% average diameter of the carrier particles falls within a range of between 35 and 90 μm.